Engine arrangements with EGR systems

ABSTRACT

Systems, apparatus, and methods are disclosed that include a divided exhaust engine with at least one pair of primary EGR cylinders and a plurality of pairs of non-primary EGR cylinders. The pair of primary EGR cylinders can be connected to an intake with an EGR system that lacks an EGR cooler. In another embodiment, the cylinder pairs include exhaust flow paths that join in the cylinder head to form a common exhaust outlet for each cylinder pair in the cylinder head that is connected directly to the EGR system or to the exhaust system without an exhaust manifold.

The present application claims the benefit of the filing date of U.S.Provisional Application Ser. No. 62/187,908 filed Jul. 2, 2015, which isincorporated herein by reference.

BACKGROUND

Engines opera tin with one or more cylinders as dedicated exhaust gasrecirculation (EGR) cylinders enjoy greatly simplified controls andpressure management, fewer hardware devices, and other benefits.However, these simplifications come at the cost of a loss of controlover the system. For example, cylinder deactivation in turbochargedsystems that include dedicated EGR can affect the exhaust flow throughthe turbocharger and the distribution of EGR flow into the intake flow.In addition, twin turbocharger arrangements require complicated plumbingarrangements, additional components, and high temperature capableexhaust manifolds, increasing cost and complexity of these systems.Therefore, further technological developments are desirable in thisarea.

SUMMARY

One embodiment is a unique system, method and/or apparatus that includesa divided exhaust engine with at least one pair of primary EGR cylindersand at least two pairs of non-primary EGR cylinders. The exhaust flowfrom the primary EGR cylinders is returned to the intake and the exhaustflow from each pair of the non-primary EGR cylinders is provided to arespective turbine in the exhaust system.

In a further embodiment, the cylinders in each cylinder pair arephysically adjacent to one another in the cylinder head so the exhaustoutlets of the cylinders in each cylinder pair are combined in thecylinder head to form a common exhaust passage or common EGR passage inthe cylinder head. The common EGR passage of the primary EGR cylinderpair is directly connected to as EGR cooler without an EGR, manifold. Insome embodiments, the EGR cooler is mounted directly to the cylinderhead at the outlet of the common EGR passage. The common exhaustpassages of the non-primary EGR cylinder pairs are each directlyconnected to a corresponding turbine mounted adjacent to the cylinderhead at the outlet of the corresponding common exhaust passage withoutan intervening exhaust manifold. In some embodiments the turbine ismounted directly to the cylinder head.

In a specific embodiment, a six cylinder engine with primary EGRcylinders is provided in which the first and second cylinders are pairednon-primary EGR cylinders and the fifth and sixth cylinders are pairednon-primary EGR cylinders, and the third and fourth cylinders are pairedprimary EGR cylinders. The exhaust flow from the third and fourthcylinders is outlet from the cylinder head directly into art EGR coolerwhere it is then returned to the intake. The exhaust flow from the firstand second cylinders is outlet from the cylinder head directly into afirst turbine, and the exhaust flow from the fifth and sixth cylindersis outlet from the cylinder head directly into a second turbine.Cylinder deactivation of a first cylinder group including the first,second and third cylinders, or deactivation of a second cylinder groupincluding the fourth, fifth and sixth cylinders, provides a properlyfunctioning three cylinder EGR engine in which the exhaust flow from oneprimary EGR cylinder that is not deactivated is returned entirely to theintake and the exhaust flow from the other two non-primary cylindersthat are not deactivated drives one of the turbines to compress intakeflow.

In still another embodiment, a six cylinder in-line engine is providedin which the first and second cylinders are physically adjacent oneanother and paired non-primary EGR cylinders and the fifth and sixthcylinders are physically adjacent one another and paired non-primary EGRcylinders, and the third and fourth cylinders are physically adjacentone another and paired primary EGR cylinders. The exhaust flow from thethird and fourth cylinders is returned directly to the intake withoutEGR cooling.

In yet another embodiment, a six cylinder V-bank engine is provided inwhich the two cylinders at one end are paired primary EGR cylinders, andthe remaining two cylinders one side of the V-bank are pairednon-primary EGR cylinders connected to a first turbocharger and the tworemaining cylinders on the other side of the V-bank are pair non-primaryEGR cylinders connected to a second turbocharger.

This summary is provided to introduce a selection of concepts that arefurther described below in the illustrative embodiments. This summary isnot intended to identify key or essential features of the claimedsubject matter, nor is it intended to be used as an aid in limiting thescope of the claimed subject matter. Further embodiments, forms,objects, features, advantages, aspects, and benefits shall becomeapparent from the following description and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic depiction of a system having an engine withprimary EGR cylinders that primarily provide or are dedicated toproviding EGR flow, and additional non-primary or secondary cylindersthat do not or typically do not contribute to EGR flow.

FIG. 2 is a schematic depiction of a top plan view of a cylinder head ofthe engine of FIG. 1 with an EGR cooler and twin turbochargers.

FIG. 3 is a schematic depiction of an elevation view of the cylinderhead, EGR cooler, and twin turbochargers of FIG. 2.

FIG. 4 is a schematic depiction of another embodiment system havingprimary EGR cylinders and non-primary EGR cylinders with an EGR passageconnected to receive exhaust flow from the exhaust passage of thesecondary EGR cylinders that are not the primary EGR cylinders.

FIG. 5 is a schematic depiction of another embodiment system having anengine with primary EGR cylinders that primarily provide or arededicated to providing FOR flow, and additional non-primary or secondarycylinders that do not or typically do not contribute to EGR flow.

DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

For the purposes of promoting an understanding of the principles of theinvention, reference will now be made to the embodiments illustrated inthe drawings and specific language will be used to describe the same. Itwill nevertheless be understood that no limitation of the scope of theinvention is thereby intended, any alterations and further modificationsin the illustrated embodiments, and any further applications of theprinciples of the invention as illustrated therein as would normallyoccur to one skilled in the art to which the invention relates arecontemplated herein.

Referencing FIG. 1, a system 10 is depicted having an engine 12. Theengine 12 is an internal combustion engine of any type, and can includea stoichiometric engine, a gasoline engine, and/or a natural gas engine.In certain embodiments, the engine 12 includes a lean combustion enginesuch as a lean burn gasoline engine or a diesel cycle engine. In certainembodiments, the engine 12 may be any engine type producing emissionsthat may include an exhaust gas recirculation (EGR) system, for exampleto reduce NO_(x) emissions from the engine 12. The engine 12 includes aplurality of cylinders 14 a, 14 b, 14 c, 14 d, 14 e and 14 f,collectively referred to as cylinders 14. The number of cylinders 14 maybe any number suitable for an engine, although certain specificembodiments contemplate a six cylinder engine. The engine arrangementmay be a six cylinder in-line arrangement as shown in FIG. 1, althoughV-shaped or other suitable arrangements are not precluded.

The engine 12 includes primary EGR cylinders 14 c and 14 d that arethird and fourth cylinders and physically adjacent one another in thein-line arrangement. Engine 12 also includes other or remainingnon-primary EGR cylinders 14 a and 14 b that are first and secondcylinders and physically adjacent one another in the in-linearrangement, and non-primary EGR cylinders 14 e and 14 f that arephysically adjacent one another and fifth and sixth cylinders in thein-line arrangement. Non-primary EGR cylinders 14 a, 14 b, 14 e and 14 fcan be completely flow isolated from the EGR system 16, as discussedfurther below. The term primary EGR, as utilized herein, should be readbroadly. Any EGR arrangement wherein, during at least certain operatingconditions, the entire exhaust output of primary EGR cylinders 14 c and14 d is recirculated to the engine intake system 18 is a primary EGRcylinder. A primary EGR cylinder typically, at least during primary EGRoperation, includes exhaust divided from one or more of the remainingcylinders that are not primary EGR cylinders.

In the system 10, the EGR flow 20 recirculates in an EGR conduit 22 andcombines with intake flow 24 at a position upstream of an intakemanifold 26 of intake system 18. Intake manifold 26 provides a chargeflow including the intake flow 24 combined with EGR flow 20. Intakemanifold 26 is connected to an intake passage 28 that includes an intakethrottle 30 to regulate the charge flow to cylinders 14. Intake passage28 may also include a charge air cooler 32 to cool the charge flowprovided to intake manifold 26.

The EGR flow 20 may combine with the intake flow 24 at an outlet of EGRconduit 22 through, for example, a restriction such as a mixer or anyother suitable arrangement (not shown.) In certain embodiments, the EGRflow 20 returns to the intake manifold 26 directly. The EGR system 16may be a low-pressure loop, for example returning to the intake at aposition upstream of a compressor in the intake system 18, or ahigh-pressure loop, for example returning to the intake at a positiondownstream of the compressor and/or at the intake manifold 26. Incertain embodiments, the system 10 includes an EGR cooler 34 betweenengine 12 and the EGR conduit 22. In other embodiments, EGR conduit 22can include a bypass with a valve that selectively allows EGR flow tobypass the EGR cooler 34. The presence of an EGR cooler bypass isoptional and non-limiting.

Referring further to FIGS. 2-3, EGR cooler 34 is mounted directly to aflow outlet of cylinder head 40 of engine 12. EGR cooler 34 could alsobe mounted directly on cylinder head 40 or the engine block. Third andfourth primary EGR cylinders 14 c, 14 d each include at least oneexhaust port 15 c, 15 d, respectively. Primary EGR cylinders 14 c, 14 dare mirrored to minimize the spacing between the exhaust ports 15 c, 15d, and the exhaust ports 15 c, 15 d of cylinders 14 c, 14 d are joinedto one another at a common EGR passage 42 formed, drilled, machined, orotherwise defined by and in cylinder head 40. EGR cooler 34 is mounteddirectly to a flow outlet of cylinder head 40 to receive the EGR flowfrom the outlet of the common EGR passage 42 and provide EGR flow 20 toEGR conduit 22 without an exhaust manifold.

First and second non-primary EGR cylinders 14 a, 14 b are also mirroredrelative to one another and each includes at least one exhaust port thatis adjacent to the exhaust port of the other mirrored non-primary EGRcylinder, and the exhaust ports from these cylinders 14 a, 14 b arejoined at a first common exhaust passage 44 a in cylinder head 40. Fifthand sixth non-primary EGR cylinders 14 e, 14 f are also mirroredrelative to one another and each includes at least one exhaust port thatis adjacent to the exhaust port of the other mirrored non-primary EGRcylinder, and the exhaust ports from these cylinders 14 e, 14 f arejoined at a second common exhaust passage 44 b in cylinder head 40.

System 10 includes an exhaust system 36 that does not include anyexhaust manifold for any of the cylinders 14. Exhaust system 36 includesan aftertreatment system 38 to treat pollutants in the exhaust beforethe exhaust is outlet to the environment. Exhaust system 36 includes afirst turbocharger 50 a and a second turbocharger 50 b. Firstturbocharger 50 a includes a first turbine 52 a and a first compressor54 a. Second turbocharger 50 b includes a second turbine 52 b and asecond compressor 54 b.

First turbine 52 a is mounted directly to a flow outlet of cylinder head40 to receive exhaust flow outlet from first common exhaust passage 44 awithout an intervening exhaust manifold. Second turbine 52 b is mounteddirectly to a flow outlet of cylinder head 40 to receive exhaust flowoutlet from second common exhaust passage 44 b without an interveningexhaust manifold. As shown in FIG. 3, turbines 52 a, 52 b can bedirectly mounted to the outlets of cylinder head 40 in a firsthorizontal plane P, and EGR cooler 34 is vertically offset or staggeredfrom plane P to allow space for mounting of the turbines 52 a, 52 b andEGR cooler 34 directly to the outlets of cylinder head 40 withoutinterfering with one another. EGR cooler 34 is shown above turbines 52a, 52 b, but could also be staggered vertically below turbines 52 a, 52b. EGR cooler 34 can also be provided with ports that plug directly intothe coolant ports of cylinder head 40 so that separate plumbing forproviding coolant flow to EGR cooler 34 is not required.

Each turbine 52 a, 52 b includes an outlet that is connected with arespective one of separate exhaust conduits 56 a, 56 b, and exhaustconduits 56 a, 56 b join a common exhaust conduit 58 that includes theaftertreatment system 38. Other embodiments contemplate separate exhaustoutlets and aftertreatment systems for each turbine 52 a, 52 b.

Turbines 52 a, 52 b are operable via the exhaust gases from therespective non-primary EGR cylinder pairs 14 a, 14 b and 14 e, 14 f todrive the respective compressor 54 a, 54 b to compress intake air flows62 a, 62 b in the respective intake conduits 60 a, 60 b, which combineat intake air cooler 32. Other embodiments contemplate separate intakeair coolers for each intake conduit 60 a, 60 b, or that an intake aircooler is omitted. Turbines 52 a, 52 b can be a variable geometryturbine with an adjustable inlet, or include a wastegate to bypassexhaust flow. Other embodiments contemplate an exhaust throttle (notshown) in the exhaust system 36.

In certain embodiments, the system 10 includes a controller 80structured to perform certain operations to control a divided exhaustgas engine such as engine 12. In certain embodiments, the controller 80forms a portion of a processing subsystem including one or morecomputing devices having memory, processing, and communication hardware.The controller 80 may be a single device or a distributed device, andthe functions of the controller 80 may be performed by hardware or byinstructions encoded on computer readable medium. The controller 80 maybe included within, partially included within, or completely separatedfrom an engine controller (not shown). The controller 80 is incommunication with any sensor or actuator throughout the system 10,including through direct communication, communication over a datalink,and/or through communication with other controllers or portions of theprocessing subsystem that provide sensor and/or actuator information tothe controller 80.

In certain embodiments, the controller 80 is described as functionallyexecuting certain operations. The descriptions herein including thecontroller operations emphasizes the structural independence of thecontroller, and illustrates one grouping of operations andresponsibilities of the controller. Other groupings that execute similaroverall operations are understood within the scope of the presentapplication. Aspects of the controller may be implemented in hardwareand/or by a computer executing instructions stored in non-transientmemory on one or more computer readable media, and the controller may bedistributed across various hardware or computer based components.

Example and non-limiting controller implementation elements includesensors providing any value determined herein, sensors providing anyvalue that is a precursor to a value determined herein, datalink and/ornetwork hardware including communication chips, oscillating crystals,communication links, cables, twisted pair wiring, coaxial wiring,shielded wiring, transmitters, receivers, and/or transceivers, logiccircuits, hard-wired logic circuits, reconfigurable logic circuits in aparticular non-transient state configured according to the modulespecification, any actuator including at least an electrical, hydraulic,or pneumatic actuator, a solenoid, an op-amp, analog control elements(springs, filters, integrators, adders, dividers, gain elements), and/ordigital control elements.)

The listing herein of specific implementation elements is not limiting,and any implementation element for any controller described herein thatwould be understood by one of skill in the art is contemplated herein.The controllers herein, once the operations are described, are capableof numerous hardware and/or computer based implementations, many of thespecific implementations of which involve mechanical steps for one ofskill in the art having the benefit of the disclosures herein and theunderstanding of the operations of the controllers provided by thepresent disclosure.

One of skill in the art, having the benefit of the disclosures herein,will recognize that the controllers, control systems and control methodsdisclosed herein are structured to perform operations that improvevarious technologies and provide improvements in various technologicalfields. Without limitation, example and non-limiting technologyimprovements include improvements in combustion performance of internalcombustion engines, improvements in emissions performance,aftertreatment system performance, engine torque generation and torquecontrol, engine fuel economy performance, improved durability of exhaustsystem components for internal combustion engines, and engine noise andvibration control. Without limitation, example and non-limitingtechnological fields that are improved include the technological fieldsof internal combustion engines and related apparatuses and systems aswell as vehicles including the same.

Certain operations described herein include operations to interpret ordetermine one or more parameters. Interpreting and determining, asutilized herein, includes receiving values by any method known in theart, including at least receiving values from a datalink or networkcommunication, receiving an electronic signal (e.g. a voltage,frequency, current, or PWM signal) indicative of the value, receiving asoftware parameter indicative of the value, reading the value from amemory location on a non-transient computer readable storage medium,receiving the value as a run-time parameter by any means known in theart, and/or by receiving a value by which the interpreted or determinedparameter can be calculated, and/or by referencing a default value thatis interpreted or determined to be the parameter value.

Certain systems are described following, and include examples ofcontroller operations in various contexts of the present disclosure. Incertain embodiments, a procedure includes an EGR flow 20 that isprovided to the intake system 18 to mix with the intake flow and providea charge flow to cylinders 14. The charge flow includes an amount ofrecirculated exhaust gas from primary EGR cylinders 14 c, 14 d.

The controller 80 is operable to interpret a cylinder deactivationcondition and deactivate a group of cylinders 14 by cutting fuel flowthereto from a fuel source 82. For example, a first group of cylindersincludes cylinders 14 a, 14 b and 14 c, and a second group of cylindersincludes cylinders 14 d, 14 e and 14 f. Deactivation of one of the firstand second groups cuts fuelling to the cylinders in the group and closesthe intake and exhaust valves to prevent airflow therethrough. Thisprovides engine operation with the other group of cylinders, effectivelyproviding a three cylinder EGR engine operation in which the route ofEGR flow 20 that is provided by the active one of the primary EGRcylinders 14 c, 14 d is unaffected, and the turbocharger operation ofthe turbine receiving exhaust flow from the active cylinder pair 14 a-bor 14 e-f is unaffected. This is not the case with prior arrangements inwhich cylinder deactivation affects turbocharger operations and/or thefraction of EGR flow in the charge flow.

The system 10 can include a fueling system with fuel source 82 and fuelinjectors connected to each of the cylinders 14. In certain embodiments,one or more or all of the cylinders 14 a, 14 b, 14 c, 14 d, 14 e, 14 fincludes a direct injector 15 a, 15 b, 15 c, 15 d, 15 e, 15 f,respectively, for providing fuel from the fueling system. A directinjector, as utilized herein, includes any fuel injection device thatinjects fuel directly into the cylinder volume, and is capable ofdelivering fuel into the cylinder volume when the intake valve(s) andexhaust valve(s) are closed. The direct injector may be structured toinject fuel at the top of the cylinder or laterally. In certainembodiments, the direct injector may be structured to inject fuel into acombustion pre-chamber. Each cylinder 14 may include one or more directinjectors. The direct injectors may be the primary or the only fuelingdevice for the cylinders 14, or alternatively the direct injectors maybe an auxiliary or secondary fueling device for the cylinders 14. Incertain embodiments, the direct injectors are capable of providing theentire designed fueling amount for the cylinders 14 at any operatingcondition. Alternatively, the direct injectors may be only partiallycapable of providing the designed fuelling fueling amount, for examplethe direct injectors may be capable of providing a designated amount offuel for a specific purpose.

In still other embodiments, one or all of the cylinders 14 include aport injector (not shown) in addition to or alternatively to directinjectors. In these embodiments, the intake manifold 26 may be divided(not shown) to separate the charge flows to the respective cylinderpairs 14 a-b, 14 c-d, and 14 e-f, or the port fuel injectors may bepositioned such that no other cylinder in the system 10 is downstream ofthe port fuel injector, i.e. only the target cylinder is downstream ofthe port fuel injector.

In certain embodiments, the controller 140 controls operation of thedirect injectors or port injectors of cylinders 14 in response to thecylinder deactivation conditions to de-fuel one of the first and secondgroups of cylinders 14. De-fuelling one of the groups provides improvedfuel economy when cylinder deactivation conditions are enabled ordetected, such as a steady state condition at certain operatingconditions and/or at low operating loads.

Referring to FIG. 4, another embodiment system 100 is shown in whichlike elements with system 10 are designated with similar referencenumerals. System 100 includes a single turbocharger 150 and exhaustmanifold portions 134 a, 134 b connected with non-primary EGR cylinderpairs 14 a-b and 14 e-f respectively; however, such as with system 10discussed above, twin turbochargers mounted directly to the cylinderhead are also contemplated. Exhaust flow from exhaust manifold portions134 a, 134 b drives turbine 152 to compress intake air flow 162 withcompressor 154. In one embodiment, turbine 152 is a twin entry turbineand each cylinder pair 14 a, 14 b and 14 e, 14 f is connected to aseparate one of the twin entries 152 a, 152 b with separate exhaustconduits 156 a, 156 b. In a further embodiment (now shown), cylinderpairs 14 a, 14 b and 14 e, 14 f each connect to respective one of firstand second exhaust manifolds that are connected to the respectiveturbine inlets.

System 100 includes an EGR system 160 connected with an EGR manifold 134c that receives an EGR flow train primary EGR cylinders 14 c-d.Therefore, the third and fourth cylinders 14, or primary EGR cylinders14 c-d, provide a high EGR fraction of 33% since there are six totalcylinders in the illustrated embodiment. EGR system 160 lacks any EGRcooler and therefore the high EGR fraction of system 100 provides NOxreduction without EGR cooling. In addition, the non-cooled, high EGRfraction allows start of ignition to be advance to reduce brake specificfuel consumption and reduction of particulate matter emissions duringcombustion optimization.

In still another embodiment shown in FIG. 5, a six cylinder V-bankengine 250 is provided in which the two cylinders 252 a, 252 b at oneend are paired primary EGR cylinders and physically adjacent oneanother. The remaining two cylinders 252 c, 252 d on one side of theV-bank are paired non-primary EGR cylinders physically adjacent oneanother and connected to a first turbocharger 254 a with first exhaustpassage 260 a. The two remaining cylinders 252 e, 252 f on the otherside of the V-bank are paired non-primary EGR cylinders physicallyadjacent to one another and connected to a second turbocharger 254 bwith second exhaust passage 260 b.

The exhaust flow 258 from the paired end cylinders 252 a, 252 b isreturned directly to the intake 256 with an EGR passage 264. In oneembodiment, an EGR cooler 262 is mounted to intake 256 to cool the EGRflow. In other embodiments, an EGR cooler is omitted.

Various aspects of the present disclosure are contemplated. In oneaspect, a system includes an internal combustion engine including atleast one pair of primary EGR cylinders connected to a common EGRpassage to provide an EGR flow to an intake of the engine and aplurality of pairs of non-primary cylinders with each non-primarycylinder pair connected to a respective one of a plurality of commonexhaust passages to provide an exhaust flow to a respective one of aplurality of turbines connected to the respective common exhaustpassage.

In one embodiment, the common EGR passage and the common exhaustpassages are formed in a cylinder head of the engine. In anotherembodiment, each of the plurality of turbines is mounted directly to thecylinder head at an outlet of the respective common exhaust passage, andthe system further includes an EGR cooler mounted to the cylinder headat an out et of the common EGR passage.

In another embodiment, each of the plurality of turbines includes acompressor in a respective intake conduit to compress an intake airflow. In a refinement of this embodiment, the compressed intake airflows from the intake conduits combine at an intake air cooler. In yetanother embodiment, the system includes an intake passage connecting theintake cooler to the intake and the manifold and the common EGR passageis connected to the intake passage downstream of the intake air cooler.In still further embodiments, each of the turbines includes an outletthat is connected with a respective one of separate exhaust conduitsthat are joined at a common exhaust conduit connected to anaftertreatment system.

In another aspect, a system includes an internal combustion engineincluding six cylinders. First and second cylinders are adjacent oneanother and flow connected to a first turbine through a first commonexhaust passage. Third and fourth cylinders are adjacent one another andflow connected to an EGR cooler through a common EGR passage and the EGRcooler is connected to an intake of the engine. Fifth and sixthcylinders are adjacent one another and flow connected to a secondturbine through a second common exhaust passage.

In one embodiment, the EGR cooler and the first and second turbines areeach flow coupled directly to a corresponding outlet of the common EGRpassage and the first and second common exhaust passages, respectively.In another embodiment, the common EGR passage and the first and secondcommon exhaust passages are formed in a cylinder head of the engine. Ina refinement of this embodiment, the first and second turbines are flowcoupled to the cylinder head in a first horizontal plane and the EGRcooler is offset vertically from the horizontal plane.

In yet another embodiment, the system includes a controller configuredto selectively deactivate one of a first group of cylinders thatincludes the first, second and third cylinders and a second group ofcylinders that includes the fourth, fifth and sixth cylinders. Thecontroller operates the internal combustion engine as a three cylinderinternal combustion engine with EGR flow from one of the third andfourth cylinders and intake air flow compressed from only one of thefirst and second turbines.

In another aspect, a system includes an internal combustion engine withsix cylinders. First and second cylinders are adjacent one another andflow connected to a first turbine through a first common exhaustpassage. Third and fourth cylinders are adjacent one another and flowconnected through a common EGR passage to an EGR conduit that isconnected to an intake manifold of the engine without an EGR coolerbetween third and fourth cylinders and the intake. Fifth and sixthcylinders are adjacent one another and flow connected to a secondturbine through a second common exhaust passage.

In one embodiment, the system includes a controller configured toselectively deactivate one of a first group of cylinders that includesthe first, second and third cylinders and a second group of cylindersthat includes the fourth, fifth and sixth cylinders. The controller isconfigured to operate the internal combustion engine as a three cylinderinternal combustion engine with EGR flow from one of the third andfourth cylinders and intake air flow compressed from only one of thefirst and second turbines.

In another embodiment, the first and second turbines are each flowcoupled directly to a corresponding outlet of the first and secondcommon exhaust passages, respectively. In a refinement of thisembodiment, the common EGR passage and the first and second commonexhaust passages are formed in a cylinder head of the engine.

In another aspect, a system includes an internal combustion enginehaving six cylinders in a V-bank. First and second cylinders along afirst side of the V-bank are adjacent one another and flow connected toa first turbine in a first exhaust passage. Third and fourth cylindersalong a second side of the V-bank are adjacent one another and flowconnected to a second turbine in a second exhaust passage. Fifth andsixth cylinders at one end of the V-banks are flow connected to an EGRcooler that is connected to an intake of the engine.

In another aspect, a system includes an internal combustion enginehaving at least one pair of primary EGR cylinders connected to a commonEGR passage to provide an EGR flow to an intake of the engine and aplurality of pairs of non-primary cylinders with each non-primarycylinder pair connected to a respective one of a plurality of commonexhaust passages to provide an exhaust flow to a respective one of aplurality of turbine inlets connected to the respective common exhaustpassage.

In one embodiment, the turbine inlets are separate inlets to a commonturbine housing. In another embodiment, the internal combustion engineis an in-line six cylinder engine with the pair of primary EGR cylindersbetween first and second pairs of non-primary EGR cylinders.

While the invention has been illustrated and described in detail in thedrawings and foregoing description, the same is to be considered asillustrative and not restrictive in character, it being understood thatonly certain exemplary embodiments have been shown and described. Thoseskilled in the art will appreciate that many modifications are possiblein the example embodiments without materially departing from thisinvention. Accordingly, all such modifications are intended to beincluded within the scope of this disclosure as defined in the followingclaims.

In reading the claims, it is intended that when words such as “a,” “an,”“at least one,” or “at least one portion” are used there is no intentionto limit the claim to only one item unless specifically stated to thecontrary in the claim. When the language “at least a portion” and/or “aportion” is used the item can include a portion and/or the entire itemunless specifically stated to the contrary.

What is claimed is:
 1. A system comprising: an internal combustionengine including; at least one pair of primary exhaust gas recirculation(EGR) cylinders; wherein an EGR flow from a pair of the at least onepair of the primary EGR cylinders is joined together to form a commonEGR passage to provide a joined EGR flow to an intake passage of theengine; and a plurality of pairs of non-primary cylinders; wherein anexhaust flow from a pair of the pairs of non-primary cylinders is joinedtogether to form one of a plurality of common exhaust passages toprovide a joined exhaust flow to a respective one of a plurality ofturbines directly connected to the respective one of the pluralitycommon exhaust passages.
 2. The system of claim 1, wherein the commonEGR passage and the plurality of common exhaust passages are formed in acylinder head of the engine.
 3. The system of claim 1, wherein each ofthe plurality of turbines is mounted directly to the cylinder head at anoutlet of the respective common exhaust passage, and further comprisingan EGR cooler mounted to the cylinder head at an outlet of the commonEGR passage.
 4. The system of claim 1, wherein each of the plurality ofturbines includes a compressor in a respective intake conduit tocompress an intake air flow.
 5. The system of claim 4, wherein thecompressed intake air flows from the intake conduits combine at anintake air cooler.
 6. The system of claim 5, further comprising anintake passage connecting the intake cooler to the intake passage of theengine and the common EGR passage is connected to the intake passage ofthe engine downstream of the intake air cooler.
 7. The system of claim6, wherein each of the turbines includes an outlet that is connectedwith a respective one of separate exhaust conduits that are joined at acommon exhaust conduit connected to an aftertreatment system.
 8. Asystem comprising: an internal combustion engine including; sixcylinders; a first turbocharger having a first compressor connected to afirst turbine; and a second turbocharger having a second compressorconnected to a second turbine; wherein first and second cylinders areadjacent one another and connected to the first turbine to deliver anexhaust gas flow through a first common exhaust passage; wherein thirdand fourth cylinders are adjacent one another and connected to anexhaust gas recirculation (EGR) cooler to deliver an exhaust gasrecirculation flow directly through a common EGR passage; wherein theEGR cooler is connected to an intake of the engine; and wherein fifthand sixth cylinders are adjacent one another and connected to the secondturbine to deliver an exhaust gas flow through a second common exhaustpassage.
 9. The system of claim 8, wherein the EGR cooler and the firstand second turbines are each flow coupled directly to a correspondingoutlet of the common EGR passage and the first and second common exhaustpassages, respectively.
 10. The system of claim 8, wherein the commonEGR passage and the first and second common exhaust passages are formedin a cylinder head of the engine.
 11. The system of claim 10, whereinthe first and second turbines are flow coupled to the cylinder head in afirst horizontal plane and the EGR cooler is offset vertically from thehorizontal plane.
 12. The system of claim 8, further comprising: acontroller configured to selectively deactivate one of a first group ofcylinders that includes the first, second and third cylinders and asecond group of cylinders that includes the fourth, fifth and sixthcylinders and operate the internal combustion engine as a three cylinderinternal combustion engine with EGR flow from one of the third andfourth cylinders and intake air flow compressed from only one of thefirst and second turbines.